This relates generally to imaging systems, and more particularly, to imaging systems with imaging devices having ultraviolet light detection capabilities.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with an array of image pixels arranged in pixel rows and pixel columns. The image pixels contain a layer of silicon that forms a photosensitive region for generating charge in response to image light. Circuitry is commonly coupled to each pixel column for reading out image signals from the image pixels.
Conventional imaging systems sample the visible light spectrum using red, green, and blue (RGB) image pixels arranged in a Bayer mosaic pattern. The photosensitive region in each of the image pixels generates an image signal in response to red, green, or blue light that is incident upon the pixel.
In some scenarios, it may be desirable to sample light outside of the visible light spectrum. For example, it may be useful to sample ultraviolet light in low-light environments or in applications such as machine vision, fracture mechanics, biology, automotive or other vehicular environment monitoring, space exploration, and spectrophotometry. However, the silicon used in the photosensitive regions of conventional imaging systems exhibits a low absorption of ultraviolet radiation, which can make it difficult to detect ultraviolet light using conventional image sensors. While the silicon used to form the photosensitive regions in conventional image sensors can be modified to increase ultraviolet absorptivity, doing so requires extensive changes to the structure and composition of the photodiode that may complicate manufacturing and increase production costs.
It would therefore be desirable to be able to provide imaging devices with improved ultraviolet light detection capabilities.